Publication

Abstract : Nanoenergetic materials with very high combustion speeds are ideal for use as green primers, kinetic rods, and reactive materials. However, their high sensitivity to ESD remains a major challenge for practical applications. These static sensitive materials may cause accidental ignition posing a major safety hazard. It is known that Al nanoparticles are typically used as the fuel component along with nano-sized metal oxides as oxidizers to prepare nanothermites. These Al nanoparticles are highly sensitive to the ESD, thereby making nanothermites vulnerable to ignition at extremely very low ESD energy. We explore the possibility of reducing the ESD sensitivity of Al nanoparticles through coating with fluoropolymers such as Teflon. Teflon being an energetic fluoropolymer is expected to sustain the reactivity of nanothermite while helping to reduce the ESD sensitivity. Well dispersed Al nanoparticles in Teflon were obtained by coating the surface of Al nanoparticles first with perfluorooctal mono-functional trimethoxy silane and then with teflon AF solution. Our measurements show that uncoated Al nanoparticles have a very low ESD energy of 0.98mJ. On the other hand, Al nanoparticles coated with 1 and 2 % of teflon have ESD energy 2.6 mJ and 4.7 mJ respectively. With increasing teflon weight to 4% and 10 %, the ESD energy increases to 25 mJ and 60mJ respectively. We have also studied the combustion properties and reactivity of the Teflon coated nanoparticles with copper oxide nanorods. Although there is a reduction in the burn rate due to Teflon coating, the peak pressure and reactivity of the material increases with the increase in percent of Teflon coating. In conclusion, our results clearly demonstrate that coating with fluoropolymers is very effective in reducing the ESD sensitivity of nanothermite materials.